From Futaba's web site:

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How do I change the frequency of my transmitter?
For a module unit: to change the frequency you simply remove the module and replace it with a module on the new channel. You can even change 'bands' (IE 72MHz to 75MHz). All radio frequency circuitry is in the module so there is no need to 'retune' after a module change. (However, the receiver cannot be similarly changed to change bands. If you go to a new band you MUST buy a new receiver on that band. Please see the note below regarding crystal changes, which is valid for ANY receiver where you are changing within one frequency band.) DO NOT attempt to change transmitter frequency by changing the crystal within the module. You must use a module which is properly tuned to the frequency desired.

For a unit with crystals: We CANNOT recommend changing crystals to a different frequency. Changing the crystal on your transmitter is illegal unless you have the proper license. The FCC has established guidelines for the modeler's safety and for the safety of spectators. For safety and FCC reasons we must request that both TX and RX be sent to the service center to ensure proper crystal change and retuning to the new frequency. Crystal based radios cannot be converted to another band without parts replacement, and may not be able to be converted at all.


BTW - I have the correct license and equipment to do this here where I work. I still send mine in so that the mfg can give the system a good going over.